1. Field of the Invention
The present invention relates to a pick-up cap, especially to a pick-up cap for a land grid array connector.
2. Description of the Prior Art
Electronic components are often manipulated for positioning on electrical apparatus as, for example, on a printed circuit board (PCB) by means of vacuum suction nozzles. In the case of an electrical connector, vacuum pick up is typically facilitated by means of a cap which have a flat upper surface and projections extending downwardly from the upper surface to engage a medial slot or a plurality of apertures of the connector. The cap and the attached connector are picked up by a vacuum suction nozzle and then placed in an appropriate position on a PCB. After the connector as well as all other components have been positioned and attached on the PCB, the vacuum pick-up cap will be removed, usually in a manual procedure.
FIGS. 4–6 show a conventional pick-up cap 98 for a land grid array (LGA) connector 9. The LGA connector 9 comprises an insulative housing 90 accommodating a plurality of conductive contacts 93, a stiffener body 92 retaining the housing 90, a load plate 96 pivotally assembled to one end of the stiffener body 92, and a load lever 97 assembled to the other end of the stiffener body 92. The load plate 96 defines a rectangular opening 960 in a middle portion thereof and a pair of pressing portions 961 surrounding the opening 960. The pick-up cap 98 defines a main body 980 and a pair of wings 981 extending from two opposite sides of the main body 980. The main body 980 is provided with a flat and smooth upper surface for being picked up by a vacuum suction nozzle. A plurality of first projections 982 extends from one of the two rest sides of the main body 980. A resilient arm 983 extends from the other of the two rest sides of the main body 980. A second projection 984 is provided at two ends of the resilient arm 983, respectively. After the pick-up cap 98 is assembled with the load plate 96, the main body 980 of the pick-up cap 98 is partially received in the opening 960, and the two wings 981 abut against the pressing portions 961 of the load plate 96. The first and second projections 982, 984 cooperatively hook the load plate 96 via the opening 960. The resilient arm 983 is convenient for assembling the pick-up cap 98 with the load plate 96 by virtue of its flexibility. Thus, the pick-up cap 98 is attached with the load plate 96 and ready for being picked up by a vacuum suction nozzle.
When the vacuum suction nozzle presses on a middle portion of the main body 980 of the pick-up cap 98, the adsorption therebetween is stable and facile. When the vacuum suction nozzle presses on a portion adjacent to the resilient arm 983, the pick-up cap-98 will endure a torsion about an axis connecting the two wings 981. But this torsion will not tilt the pick-up cap 98 because of the hooking cooperation between the first projections 982 and the load plate 96. Therefore, when the nozzle presses on a portion adjacent to the resilient arm 983, the adsorption therebetween is still stable and facile.
However, when the nozzle presses on a portion adjacent to the first projections 982, the pick-up cap 98 will be tilted, and the portion where the nozzle presses on will be pushed down toward the contacts 93. This different result is caused by the resilient arm 983. Because the resilient arm is flexible and the second projections 984 can be divorced from the load plate 96 easily. When the nozzle presses on a portion adjacent to the first projections 982, a torsion about an axis connecting the two wings 981 will force the resilient arm 983 to divorce from the load plate 96. Thus, the pick-up cap 98 is tilted and the portion where the nozzle presses on is pushed down toward the contacts 93. Once the pick-up cap 98 is tilted, the adsorption between the nozzle and the pick-up cap 98 is failed. Moreover, the contacts 93 received in the housing 90 will be bended or damaged.
In view of the above, it is strongly desired to provide an improved pick-up cap which overcomes the above-mentioned disadvantages.